From what I gathered with my imperfect data, almost nobody was using the app as a PWA even with an in-app nudge for it. I instantly got lots of downloads when I released iOS and Android apps. My users just don't want PWAs for the most part it seems.

That's typical. I think it's mainly familiarity, which in turn comes from PWAs missing basic capabilities in the past or present so everyone made apps instead. Push notifications in PWAs is a recent thing. PWAs don't share cookies with browsers, which entirely breaks some auth flows like Firebase. It's still hard to tell users to install it as you mentioned. And PWAs didn't even exist at some point.

The other thing is, many websites have bad or broken PWAs. It's usually just the website without tabs or back arrow, which sometimes makes navigation awkward because they built it assuming a browser. I'll always use the browser over the PWA.